Yarn tensioning device



Dec. 26, 1961 v. H. BUTLER 3,014,356

YARN TENSIONING DEVICE Filed Jan. 15, 1960 2 Sheets-Sheet 1 INVENTOR film /#6430715? ATTORNEYS Dec. 26, 1961 v. H. BUTLER YARN TENSIONING DEVICE Filed Jan. 15, 1960 2 Sheets-Sheet 2 0 5 6 3 7 1 g 4 8 k k w 7/uk k k 1!; w w u Y w w b k #54 g F vi &\ 3 n w ATTORNEYS 3,0143% Patented Dec. 26, 1961 3,014,356 YARN TENSIONING DEVICE Vaughn H. Butler, Harriman, Tenn, assignor to Burlington Industries, Inc., Greensboro, N.C., a corporation of Delaware Filed Jan. 15, 1960, Ser. No. 2,620 6 Claims. (Cl. 66-146) yarn tensioning device for circular knittingv machines,

adapted to feed yarn in a straight vertical path with uniform tension, whereby improved knitting is effected, and variations in product length are minimized. The tension device is particularly adapted to eliminate multiplication of variations in yarn package delivery tension.

Another object of the invention is to provide a yarn tensioning device for textile machinery, which is adapted to prevent and/ or take up slack in the yarn, such as may occur between periods of yarn feeding'and the like. Further objects will be in part evident and in part pointed out hereinafter.

The invention and the novel features thereof may be made clear from the following description and the accompanying drawings, in which:

FIGURE 1 is a side elevational view, partly diagrammatic, of an exemplary embodiment of the present invention associated with a circular knitting machine;

FIGURE 2 is a top plan view of the yarn tensioning device, on enlarged scale; I

FIGURE 3 is a side elevational view of the tensioning device;

FIGURE 4 is a transverse sectional view through the tensioning device taken substantially on the line 44 of FIGURE 2, and Y FIGURE 5 is a sectional view taken on the line 55 of FIGURE 4. Y

Referring to the drawings, FIGURE 1 illustrates the conventional components of a circular knitting machine required for an understanding of the present invention, including the dial 10 encircled by a circle of independent needles l2. Adjacent the needle circle, a plurality of yarn feed fingers 14 are pivotally mounted at 16, and a thrust rod 18 is operatively associated with each yarn feed finger, and adapted to raise the associated finger from the active position 14' to the inactive position 14". Generally above the yarn feed fingers is mounted a guide plate 20, the guide plate supporting an eye 22 through which is threaded a yarn passing to and through each yarn feed finger employed in the knitting.

24 indicates the conventional. bobbin stand rod of the machine, which supports adjacent its upper end the bobbin stand 26,.wbich mounts, as will be understood, the yarn bobbins or packages employed in the knitting. In the drawing is showna single yarn package 28 which is mounted under the bobbin stand 26, the top mounting of the yarn package being preferred for reasons appearing below. t

Between the yarn package 28 and the yarn fingers 14 is mountedthe yarn tensioning device of the invention, indicated generally by the numeral 30.- As shown, the yarn tensioning device is "supported through its bracket 32 byan arm 34 extending from the bobbin stand rod 24. The yarn 36 illustrated extends from the yarn package 2% downwardly through the yarn tensioning device 30, guide plate and yarn feed finger 14", the arrangement being such that the yarnipath is substantially a straight line and vertical, whereby the yarn 36 is subjected to minimum frictional contact.

A compressed air line 40 leads to inlet nipple 42 of the tensioning device, the compressed air line being provided with a valve 44 and a metering valve 46, which may be a constant pressure outlet valve, as shown. The valve 44 may be operated by the main drum of the machine, conveniently by the diagrammatically indicated linkage 48 extending from the valve to the thrust rod 18, whereby the valve may be open when the thrust rod is in lower position and the associated feed finger in active position, and the valve closed when the thrust rod is elevated to displace the associated feed finger to inactive position.

The yarn tensioning device is illustrated in detail in FIGURES 2-5, and comprises a cylindrical body 50, from the lower end of which the bracket 32 extends laterally. The body 50 is centrally drilled to receive bushing members 52 and 54. The upper bushing 52 is provided with a small diameter axial passage 56, which terminates at its lower end in the outwardly flaring surface 58. The lower bushing 54 is similarly provided with a small diameter axial passage 60, which terminates at its upper end in an outwardly flaring surface 62. As shown, the pas sages 56 and 60 are in alignment, and the surfaces 58 and 62 are in facing relationship, defining therebetween an enlarged compartment 64. Below the flaring surface 62, the

lower bushing member 54 is provided with an annular chamber 66 encircling the passage 60, and a passage 68 extending through the inlet nipple 42 and the body 50 provides communication between the annular chamber 66 and the exterior of the body., A plurality of restricted bores 70 extend from the annular chamber 66 to the flaring surface 58, that is to the compartment 64. As best shown in FIGURE 4, the restricted bores 70 are angulated with respect to the axis of the device, each bore I axis intersecting the bushing axis and approaching inwardly and upwardly with respect thereto. The bores may be three in number, as illustrated in FIGURE 5, and equally angularly spaced.

Above the body 50 are mounted a series of plate baffles 72, the bafiies being uniformly spaced from each other and from the top of the body 50 by means of spacers 74. The spacers 74 may be in the form of sleeves, and the baffles and spacers conveniently mounted atop the tensioning device body by means of extended bolts 76, which extend through the baflles and spacers and are threadably engaged to the body. The plate baffies may be circular, and each is provided with an opening 73 which encircles the center of the baffle. Since the baffles and body 50 are aligned, each bafile opening 78 encircles also the axis of the passages 56 and 60. For reasons presently apparent, the'bafile openings are each slightly offset from center, and the battles are arranged whereby the openings are offset also with respect to the corresponding openings of adjacent baffles. For example, as shown in FIGURE 4, the opening 78 of the lowermost bafile is offset slightly to the right. The opening of the plate bafile next above is offset slightly to the left, the opening of the bafiie next above is offset slightly to the right, and so forth.

Nylon monofilament yarn, for example 15 denier, is now available in free delivery packages, and it is essential to add tension to the yarn in order to effect knitting of good quality.

While the yarn delivery tension may be very low, it exhibits wide variation between packages, and sometimes between parts of packages, and the maximum delivery tension may be as much as twice as great as the minimum delivery tension. For example, the delivery tension of the yarn package 28 may range between .01 and .02 gram.

For good knitting, the yarn 36 should be delivered to the needles 12 with a minimum tension of one-half gram. The tension may be greater, but no advantage appears to follow from the use of tension exceeding one-half gram. It has been noted that conventional tensioning devices associated with circular knitting machines, with necessary thread guides and the like, exhibit a multiplying effect with respect to variations in delivery tension of the package. For example, if the delivery tension of the package is .01 gram, and the conventional tensioning mechanism is adjusted to add one-half gram tension, the tension of the yarn delivered to the knitting needles may be .51

'gram. When the delivery tension of the yarn is increased to .02 gram, however, the variation appears to be greatly multiplied by the conventional tensioning mechanism, and the tension of the yarn delivered to the needles may rise to as much as 2.5 grams, whereby the slight difference in delivery tension of the bobbin may cause a five to one variation in tension of the yarn delivered to the needles. This wide variation in delivery tension may cause tight rings in the stockings, and is a major cause of length variation in the stockings.

In the operation of the present invention, when the yarn finger 14 is dropped to active position, by move ment of the main drum of the machine and the appropriate thrust rod 18, the yarn 36 is engaged by the needles 12 and begins to knit. Simultaneously, by means of linkage 48, valve 44 is opened, whereby compressed air passes through line 40 and passage 68 of the inlet nipple 42 of the tensioning device, to the annular chamber 66.

Pressure in the annular chamber 56 causes fine, high velocity jets of air to pass through the bores 70 into the compartment 64, as illustrated by arrows in FIGURE 4, the jets converging on the yarn 36. The yarn movement is of course in downward direction, and the impingement of the air jets is in upward direction. After convergence of the air jets, the combined air stream flows upwardly through the passage 56. The impingement of the air jets and the upward fiow of air are effective to center the length of yarn passing through the upper bushing 52, and to exert a restraining effect on its downward movement, whereby the yarn is tensioned. By way of example, the passage 56 may be one-sixteenth of an inch in diameter, the length of passage 56 may be two inches, the bores 70 .018 inch in diameter, and the air pressure in line 40 in the neighborhood of 40 lbs. per square inch. Under these conditions, approximately one-half gram tension will be exerted on a 15 denier monofilament nylon yarn.

The exemplary dimensions appearing above may obviously be varied as desired, to effect more or less tension, to accommodate yarns of different size and character, and the like. The tensioning effect of the device is most easily controlled by controlling the air pressure in line 40. Constant air pressure in the line 40, and accordingly constant and uniform tensioning effect, are accomplished by means of the valve 46. To vary the tensioning effect of the device, it is necessary only to adjust the delivery pressure of the valve 46.

The tensioning device is particularly advantageous in that its tensioning effect not only remains constant through prolonged operation under varying conditions, but also in that its tensioning effect appears to be merely additive. In the arrangement illustrated, for example, if the delivery tension of the yarn package 28 varies between .01 and .02 gram, and the tensioning device 30 is adjusted to exert one-half gram of tension, the tensionof the yarn as delivered to the knitting needles will vary substantially between .51 and .52 gram, an extremely small variation which does not detract from the quality of the stockings. As illustrated in FIGURE 1, the tensioning device functions best in a vertical in-line arrangement. The preferred position of the yarn package 28 is inverted, and supported from the top, whereby the yarn may be drawn directly downwardly without passage over or through guides or the like.

The air flow issuing from the top of passage 56 of the tensioning device has some tendency, especially when the tensioning device is located closely below the yarn package, to disturb the yarn on the package and particularly the bight of yarn extending therefrom. In some cases, this disturbance may cause objectionable variations in tension of the yarn delivered to the needles. This possibility is obviated by the plate bafllles 72, which dissipate the air flow laterally without forcibly contacting the yarn length passing therethrough, to the extent that no appreciable flow of air emerges upwardly from the uppermost plate bafile. As will be understood in connection with FIGURE 4, the opening 78 in the lowermost plate bafile 72, due primarily to its offset position, deflects some of the upward air flow issuing from the passage 56 laterally, but permits passage of a substantial proportion thereof. The opening 78 of the baffle next above, being offset with respect to the lower opening 78, dissipates more of the upward air fiow in lateral direction, permit-ting passage of a lesser proportion. In other words, the openings 78 define a sinuous path, which insures that only velocity air issues in upward direction from the opening 78 of the uppermost plate baffle.

The number and size of the bores 70 are, of course, subject to considerable variation. Two, four or more bores may be used with equal facility, or the bores may be replaced by a thin annular slot, it being necessary only that a balanced air flow of appropriate velocity be directed toward the yarn. While the invention has been illustrated in association with a circular knit-ting machine, it will be evident that it may be used with any textile machine wherein yarn feed at uniform and controllable tension is advantageous.

It will thus be seen that there has been provided by this invention a structure in which the various objects hereinbefore set forth, together with many practical advantages, are successfully achieved. As various possible embodiments may be made of the mechanical features of the above invention, all without departing from the scope thereof, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.

I claim:

1. In combination, a textile machine comprising a yarn feed finger, a yarn package mounted generally above said feed finger, and a yarn tensioning device mounted between said yarn package and said feed finger in substantially vertical alignment therewith, said tensioning device including a body having a passage extending ventically therethrough, means for causing air movement in upward direction through said passage, and a series of plate bafiies mounted above said tensioning device in successively spaced relation thereto, each of said bafiles having an opening encircling the axis of said passage, the openings of adjacent baffles being slightly offset with respect to each other.

2. In combination, a circular knitting machine comprising a yarn feed finger, a yarn package mounted generally above said feed finger, and a yarn tensioning device mounted between said yarn package and said feed finger in substantially vertical alignment therewith, said tensioning device including a body having a passage extending vertically therethrough, means for causing air movement in upward direction through said passage, and a series of plate baffles mounted above said tensioning device in successively spaced relation thereto, each of said baffies having an opening encircling the axis of said passage, the openings of adjacent bafiles being slightly offset with respect to each other.

3. The combination defined in claim 2, wherein said yarn package is top mounted.

, 4. In combination, a circular knitting machine comprising a yarn feed finger, a yarn package mounted generally above said feed finger, and a yarn tensioning device mounted between said yarn package and said feed finger in substantially vertical alignment therewith, said tensioning device including a body having a passage extending vertically therethrough, an annular chamber encircling said passage at a point spaced from the topthereof, conduit means communicating said chamber and with the exterior of said body, a plurality of restricted bores extending from said chamber to said passage, said boresbeing directed toward the axis of said passage and being angulated whereby they approach said axis inwardly and upwardly, and a series of plate baffles mounted above said tensioning device in successively spaced relation thereto, each of said baflles having :an opening encircling the axis of said passage, the openings of adjacent baffles being slightly offset with respect to each other.

5. A yarn tensioning device including va body having a passage extending vertically therethrough, means for causing air movement in upward direction through said passage, and a series of plate baifies mounted above said tensioning device in successively spaced relation thereto, each of said bafiles having an opening encircling the axis of said passage, the openings of adjacent bafiles being slightly offset with respect to each other.

6. A yarn tensioning device comprising a body having a passage extending vertically therethrough, an annular chamber encircling said passage at a point spaced from the top thereof, conduit means communicating with said chamber and with the exterior of said body, a plurality of restricted bores extending from said chamber to said passage, said bores being directed toward the of said passage and being angulated whereby they approach said axis inwardly and upwardly, and a series of plate baflles mounted above said tensioning device in successively spaced relation thereto, each of said baflles having an opening encircling the axis of said passage, the openings of adjacent baffles being slightly offset with respect to each other.

References Cited in the file of this patent UNITED STATES PATENTS 1,046,822 Madden Dec. 10, 1912 1,853,020 Page Apr. 5, 1932 2,472,614 Pens June 7, 1949 2,693,096 Quinn Nov. 2, 1954 2,790,298 Kunzle Apr. 30, 1957 2,896,435 Berg July 28, 1959 2,944,414- Malloy et a1 July 12, 1960 FOREIGN PATENTS 1,070,264 Fnance July 21, 1954 

